Auxiliary liver by transplanted frozen-thawed hepatocytes

Abstract

Among the therapeutic alternatives to orthotopic liver transplantation, hepatocyte transplantation (HT) offers the best potential in a number of liver diseases, mainly inborn errors of metabolism. Nevertheless, HT presents several inconveniences such as the scarce knowledge of the functionality of the transplanted hepatocytes, which has given rise to controversy about the specificity or unspecificity of the transplant, and the lack of a suitable system for preserving the cells. This study was designed to test a system for cryopreserving hepatocytes and to assess their functionality over prolonged periods after their ectopic transplantation. A medium and a freezing schedule which are reproducible and yield elevated viability have been used, and a number of hepatospecific parameters have been assessed: the activity of ornithine carbamoyltransferase—an enzyme of primary importance in the urea cycle—lipogenesis, gluconeogenesis, glucose-6-phosphatase and cytochrome oxidase activities, the presence of albumin—as an index of plasma protein synthesis—and IDA uptake and metabolism, showing the UDP-glucuronyl transferase activity. As dedifferentiation markers, γ-glutamyl transpeptidase and α-fetoprotein have been studied. From the results, it can be deduced that hepatocytes can be cryopreserved and transplanted and that under these conditions they maintain hepatic features for a long time. Following transplantation, several specific liver functions appear or are enhanced in the spleen. Freshly isolated and cryopreserved transplanted hepatocytes have similar behaviors, although a difference in the expression of the function can be observed. It can be concluded, then, that cryopreserved transplanted hepatocytes develop into what could be referred to as an “ectopic liver,” with the implications that this phenomenon could have in the clinical potential of this kind of transplant.